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100 lines
3.9 KiB
C
100 lines
3.9 KiB
C
/*-------------------------------------------------------------------------
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*
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* relscan.h
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* POSTGRES relation scan descriptor definitions.
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*
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*
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* Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/access/relscan.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef RELSCAN_H
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#define RELSCAN_H
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#include "access/genam.h"
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#include "access/heapam.h"
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typedef struct HeapScanDescData
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{
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/* scan parameters */
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Relation rs_rd; /* heap relation descriptor */
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Snapshot rs_snapshot; /* snapshot to see */
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int rs_nkeys; /* number of scan keys */
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ScanKey rs_key; /* array of scan key descriptors */
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bool rs_bitmapscan; /* true if this is really a bitmap scan */
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bool rs_pageatatime; /* verify visibility page-at-a-time? */
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bool rs_allow_strat; /* allow or disallow use of access strategy */
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bool rs_allow_sync; /* allow or disallow use of syncscan */
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/* state set up at initscan time */
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BlockNumber rs_nblocks; /* number of blocks to scan */
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BlockNumber rs_startblock; /* block # to start at */
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BufferAccessStrategy rs_strategy; /* access strategy for reads */
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bool rs_syncscan; /* report location to syncscan logic? */
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/* scan current state */
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bool rs_inited; /* false = scan not init'd yet */
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HeapTupleData rs_ctup; /* current tuple in scan, if any */
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BlockNumber rs_cblock; /* current block # in scan, if any */
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Buffer rs_cbuf; /* current buffer in scan, if any */
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/* NB: if rs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
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ItemPointerData rs_mctid; /* marked scan position, if any */
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/* these fields only used in page-at-a-time mode and for bitmap scans */
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int rs_cindex; /* current tuple's index in vistuples */
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int rs_mindex; /* marked tuple's saved index */
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int rs_ntuples; /* number of visible tuples on page */
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OffsetNumber rs_vistuples[MaxHeapTuplesPerPage]; /* their offsets */
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} HeapScanDescData;
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/*
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* We use the same IndexScanDescData structure for both amgettuple-based
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* and amgetbitmap-based index scans. Some fields are only relevant in
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* amgettuple-based scans.
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*/
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typedef struct IndexScanDescData
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{
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/* scan parameters */
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Relation heapRelation; /* heap relation descriptor, or NULL */
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Relation indexRelation; /* index relation descriptor */
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Snapshot xs_snapshot; /* snapshot to see */
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int numberOfKeys; /* number of index qualifier conditions */
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int numberOfOrderBys; /* number of ordering operators */
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ScanKey keyData; /* array of index qualifier descriptors */
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ScanKey orderByData; /* array of ordering op descriptors */
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/* signaling to index AM about killing index tuples */
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bool kill_prior_tuple; /* last-returned tuple is dead */
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bool ignore_killed_tuples; /* do not return killed entries */
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bool xactStartedInRecovery; /* prevents killing/seeing killed
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* tuples */
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/* index access method's private state */
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void *opaque; /* access-method-specific info */
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/* xs_ctup/xs_cbuf/xs_recheck are valid after a successful index_getnext */
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HeapTupleData xs_ctup; /* current heap tuple, if any */
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Buffer xs_cbuf; /* current heap buffer in scan, if any */
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/* NB: if xs_cbuf is not InvalidBuffer, we hold a pin on that buffer */
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bool xs_recheck; /* T means scan keys must be rechecked */
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/* state data for traversing HOT chains in index_getnext */
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bool xs_hot_dead; /* T if all members of HOT chain are dead */
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OffsetNumber xs_next_hot; /* next member of HOT chain, if any */
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TransactionId xs_prev_xmax; /* previous HOT chain member's XMAX, if any */
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} IndexScanDescData;
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/* Struct for heap-or-index scans of system tables */
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typedef struct SysScanDescData
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{
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Relation heap_rel; /* catalog being scanned */
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Relation irel; /* NULL if doing heap scan */
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HeapScanDesc scan; /* only valid in heap-scan case */
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IndexScanDesc iscan; /* only valid in index-scan case */
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} SysScanDescData;
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#endif /* RELSCAN_H */
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